cleanup: remove dead views and unused i18n keys

Delete personnes_impliquees.html.haml and reaffectation.html.haml
(now served via redirect 301). Remove tab_steps.involved_persons
and tab_steps.reaffectation i18n keys from both locales.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mfo

app/views/instructeurs/dossiers/personnes_impliquees.html.haml

@@ -440,9 +440,7 @@ en:
           private_annotations: Private annotations
           external_opinion: External opinion
           messaging: Messaging
-          involved_persons: Involved persons
           follow_up_and_decision: Follow-up and decision
-          reaffectation: reassignment
           attachments: Attachments
           rendez_vous: Appointment
         suivi_et_decision:

app/views/instructeurs/dossiers/reaffectation.html.haml

@@ -443,9 +443,7 @@ fr:
           private_annotations: Annotations privées
           external_opinion: Avis externes
           messaging: Messagerie
-          involved_persons: Personnes impliquées
           follow_up_and_decision: Suivi et décision
-          reaffectation: Réaffectation
           attachments: Pièces jointes
           rendez_vous: Rendez-vous
         suivi_et_decision:

config/locales/en.yml

@@ -32,7 +32,6 @@ en:
         success: "The file n° %{dossier_id} has been re-assigned to « %{label} » group."
         error: "Please select a group in the list below"
       reaffectation:
-        title: "Reassign the file n° %{dossier_id} to another group"
         hint:
           one: "This file is assigned to group « %{label} ». You can reassign it to the other group"
           other: "This file is assigned to group« %{label} ». You can reassign it to one of the %{count} other groups"